Juanita Jones Abernathy, Civil Rights icon and wife of the late Rev. Ralph David Abernathy, has died at age 89.

Abernathy’s family confirmed her passing in a media statement released Thursday night, but did not disclose the cause of her death.

Abernathy was deeply involved in and witness to the Civil Rights Movement, including writing the business plan for the Montgomery Bus Boycott. She and Rev. Abernathy were close friends with Martin Luther King Jr. and his wife, Coretta Scott King, and was part of King’s inner circle of advisors. Rev. Abernathy and King co-founded the Southern Christian Leadership Conference.

It was while her husband and King were in Atlanta setting up the SCLC, that Abernathy survived the bombing of her home in Montgomery by white supremacists. She received countless death threats as she worked to register black voters and integrate schools.

A longtime resident of Atlanta, Abernathy would go on to become a member of the MARTA board and the Fulton County Development Authority. Rev. Abernathy died of a heart attack in 1990 at age 64.

Abernathy died at Piedmont Hospital surrounded by her three remaining children and four grandchildren. Funeral and memorial service details have not been released.